We used them last year in Sept. when DH and I went to DLR. We flew into SNA. Fox was great. They didn't have the size car we had ordered so they upgraded us to the next level for the same price.
They are not in the airport, though. You have to take a shuttle from the airport to their store. It is really close and didn't take us very long. Plus they give you a really great map for the area and we used it a lot. In fact, we still have it and use it on our trips now.
They are a reputable company (to me) and were very nice with good customer service. We would use them again if we needed to. When we flew in March we looked for them at another airport and they didn't have a store there, we were disappointed since we had used them before and really liked them.
HTH!!